C. Rüster, T. Borzenko, C. Gould, G. Schmidt, L.W. Molenkamp, X. Liu, T.J. Wojtowicz,, J.K. Furdyna, Z.G. Yu, M.E. Flatté Very large magnetoresistance in lateral ferromagnetic (Ga,Mn)As wires with nanoconstrictions Phys. Rev. Lett. 91 (21) (2015-02-24 16:19:09), 216602/1-216602/4
We have fabricated (Ga,Mn)As nanostructures in which domain walls can be pinned by sub-10 nm constrictions. Controlled by shape anisotropy, we can switch the regions on either side of the constriction to either parallel or antiparallel magnetization. All samples exhibit a positive magnetoresistance, consistent with domain-wall trapping. For metallic samples, we find a magnetoresistance up to 8%, which can be understood from spin accumulation. In samples where, due to depletion at the constriction, a tunnel barrier is formed, we observe a magnetoresistance of up to 2000%. http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.91.216602 |